OpenGL 로 간단하게 2D Drawing 하는 기본 소스

OpenGL 로 간단하게 2D 드로잉 하는 걸 공부하고 있는데 진도가 느리다.



아래 소스는 Visual C++ 에서 OpenGL을 이용하여 간단하게 2D 드로잉을 하는 기본 소스이다.

// stdafx.h
////////////////////////////////////////////////////////////////////////////////
// for OpenGL
#pragma comment (lib, "opengl32.lib")
#pragma comment (lib, "glu32.lib")
#pragma comment (lib, "glaux.lib")

#include <gl/GL.h>
#include <gl/GLU.h>
#include <gl/GLAux.h>
// for OpenGL
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
// Header
    HGLRC    m_hRC; //Rendering Context
    CDC*     m_pDC; //Device Context
    int      m_nPixelFormat;

    BOOL InitializeOpenGL();
    void RenderScene();
    
    
////////////////////////////////////////////////////////////////////////////////
// Source
int CGLTestView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (CView::OnCreate(lpCreateStruct) == -1)
        return -1;

    InitializeOpenGL();

    return 0;
}

BOOL CGLTestView::InitializeOpenGL()
{
    //Get a DC for the Client Area
    m_pDC = new CClientDC(this);

    //Failure to Get DC
    if(m_pDC == NULL)
    {
        MessageBox( _T("Error Obtaining DC") );
        return FALSE;
    }

    ////////////////////////////////////////////////////////////////////////////////
    // Setup Pixel Format
    static PIXELFORMATDESCRIPTOR pfd = 
    {
        sizeof(PIXELFORMATDESCRIPTOR),    // size of this pfd
        1,                                // version number
        PFD_DRAW_TO_WINDOW |              // support window
        PFD_SUPPORT_OPENGL |              // support OpenGL
        PFD_DOUBLEBUFFER,                 // double buffered
        PFD_TYPE_RGBA,                    // RGBA type
        32,                               // color depth
        0, 0, 0, 0, 0, 0,                 // color bits ignored
        0,                                // no alpha buffer
        0,                                // shift bit ignored
        0,                                // no accumulation buffer
        0, 0, 0, 0,                       // accumulation bits ignored
        32,                               // z-buffer
        0,                                // no stencil buffer
        0,                                // no auxiliary buffer
        PFD_MAIN_PLANE,                   // main layer
        0,                                // reserved
        0, 0, 0                           // layer masks ignored
    };

    int m_nPixelFormat = ::ChoosePixelFormat( m_pDC->GetSafeHdc(), &pfd );

    if ( m_nPixelFormat == 0 )
    {
        return FALSE;
    }

    if ( ::SetPixelFormat( m_pDC->GetSafeHdc(), m_nPixelFormat, &pfd ) == FALSE )
    {
        return FALSE;
    }
    ////////////////////////////////////////////////////////////////////////////////

    //Create Rendering Context
    m_hRC = ::wglCreateContext( m_pDC->GetSafeHdc() );

    //Failure to Create Rendering Context
    if( m_hRC == 0 )
    {
        MessageBox( _T("Error Creating RC") );
        return FALSE;
    }

    //Make the RC Current
    if( ::wglMakeCurrent ( m_pDC->GetSafeHdc (), m_hRC ) == FALSE )
    {
        MessageBox( _T("Error making RC Current") );
        return FALSE;
    }

    //Specify Black as the clear color
    ::glClearColor( 0.0f, 0.0f, 0.0f, 0.0f);

    //Specify the back of the buffer as clear depth
    //::glClearDepth( 1.0f );

    //Enable Depth Testing
    //::glEnable( GL_DEPTH_TEST );
    ::glDisable( GL_DEPTH_TEST ); // For 2D

    return TRUE;
}

void CGLTestView::OnDraw(CDC* /*pDC*/)
{
    CGLTestDoc* pDoc = GetDocument();
    ASSERT_VALID(pDoc);
    if (!pDoc)
        return;

    // 컬러버퍼와 깊이버퍼를 초기화
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    RenderScene();

    // Tell OpenGL to flush its pipeline
    ::glFinish();

    // Now Swap the buffers
    ::SwapBuffers( m_pDC->GetSafeHdc() );
}

void CGLTestView::RenderScene()
{
    glBegin(GL_TRIANGLES);
    {
        glVertex2f(  0.0f,  0.0f );
        glVertex2f( 20.0f,  0.0f );
        glVertex2f(  0.0f, 20.0f );
    }
    glEnd();
}

void CGLTestView::OnSize(UINT nType, int cx, int cy)
{
    CView::OnSize(nType, cx, cy);

    GLdouble aspect_ratio; // width/height ratio

    if ( 0 >= cx || 0 >= cy )
    {
        return;
    }

    // select the full client area
    ::glViewport(0, 0, cx, cy);

    // compute the aspect ratio
    // this will keep all dimension scales equal
    aspect_ratio = (GLdouble)cx/(GLdouble)cy;

    // select the projection matrix and clear it
    ::glMatrixMode(GL_PROJECTION);
    ::glLoadIdentity();

    // select the viewing volume
    //::gluPerspective(45.0f, aspect_ratio, .01f, 200.0f);

    GLfloat nRange = 50.0f;
    if (cx <= cy)
    {
        glOrtho(-nRange, nRange, -nRange * cy / cx,
            nRange * cy / cx, -nRange, nRange );
    }
    else
    {
        glOrtho(-nRange * cx / cy,
            nRange * cx / cy,
            -nRange, nRange, -nRange, nRange);
    }

    // switch back to the modelview matrix and clear it
    ::glMatrixMode(GL_MODELVIEW);
    ::glLoadIdentity();
}

결과 화면

glut를 사용하지 않고 기본으로 포함되어있는 OpenGL 만을 이용한 소스이다. 분석을 하여 나중에는 glut까지 이용하는 코드를 작성해 보아야겠다.

GLTest.7z
Original Post : http://neodreamer-dev.tistory.com/274